The scribe tool of a conventional scribing machine for scribing semiconductor wafers is comprised of a relatively long shank provided with a diamond head at the normally lowermost end thereof. The diamond head, during manufacture of the tool, is lapped and polished to provide the necessary facets therefor so that the side margins of certain facets will present scribe edges that can be used to scribe an article when the tool is secured to a floating arm of the scribing machine.
It is extremely important that the facets of the diamond head be properly oriented with respect to the direction of movement of the floating arm relative to the wafer to be scribed to prevent creation of lateral stresses in the wafer which cause fractures in the structure thereof transverse to the desired scribe line. These fractures propagate through the wafer and destroy its structural integrity. As a result, some of the semiconductor chips which are obtained when the scribed wafer is broken will be imperfect and not usable. Thus, the yield from a particular wafer is minimized.
To avoid this problem, attempts have been made to provide some type of correlation between the locations of the scribe edges of the diamond head and the way in which the shank of the tool is mounted on or secured to the floating arm. For instance, flats on the shank have been used as the reference surfaces for aligning the facets of the head. However, this technique lacks the latent precision needed for radial orientation resulting in improper alignment of the scribe edges relative to the direction of tool movement relative to the article to be scribed.
A need has, therefore, arisen for improvements in either or both the scribe tool and the tool mount of a scribing machine to avoid the errors in alignment of the scribe edges of the tool relative to a desired scribe direction to thereby avoid structural damage to the article to be scribed and, in the case of semiconductor wafers, to increase the yield from a particular wafer.